PSI - Issue 44

M. Castellani et al. / Procedia Structural Integrity 44 (2023) 1084–1091 M. Castellani et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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1. Introduction Historic masonry buildings have a growing economic and social value in many countries. Preservation of the built heritage is considered an important goal in modern societies as, in addition to their historical interest, historical buildings significantly contribute to economy in a context where tourism has become a major industry. Preserving historic constructions is therefore not only a cultural requirement but also an economic and developmental demand (Bowitz et al. (2009), Galassi et al. (2022), Ruccolo et al. (2021), Zini et al. (2022)). In this context, in-depth analyses focused not only to the extreme load effects, but also to the aging and degradation of materials are fundamental for a comprehensive study of the monuments (Cavalagli et al. (2019), Biscarini et al. (2020), Hatir et al. (2021), Pepi et al. (2021)). The dynamic behavior of monuments that are as fascinating as they are articulated cannot be easily interpreted by simple mechanical models due to the large uncertainties, affecting both the materials and structural behavior, that can come into play. In this work, a multidisciplinary approach is presented which has allowed to learn and model, with a high degree of confidence, the dynamic behavior of a monument, useful for the design of a subsequent seismic isolation intervention. The Tabernacle of the main altar of the church of Santa Maria Maggiore in Spello, conceived by Rocco di Tommaso da Vicenza in the early 1500s, is one of the “ masterpieces of Renaissance sculpture in Umbria ” . Made entirely of caciolfa stone (Focaoaru (1994)), the construction rests on four finely decorated pedestals, from which four Corinthian-style columns rise (Fig. 1.a), also rich in friezes and decorations, which support, through four circular arches, a hemispherical dome including a base of square shape in plan (Fig. 1.b). Each of the four arches presents at the impost a system of tie rods for the containment of the horizontal thrusts having a squared cross section of about 4 cm of side, presumably dating back to the construction phase of the artifact, and a temporary system of additional recently installed tie rods consisting of high strength steel cables (Fig. 1.c).

Fig. 1. (a) Tabernacle from aisle side; (b) Detail of the dome; (c) System of tie rods.

The structure is regular in plan, square in shape with a side of about 4.00 m. The columns develop to a height of 3.00 m, from the base to the top of the capitals, from which the circular arches stand on with a radius of curvature at the intrados of about 1.75 m. The structure above the four arches reaches 5.65 m in height, from which the